1. Field of the Invention
The present invention relates to a pulse signal generator, a coil bobbin for the pulse signal generator and a method of making the coil bobbin.
2. Description of the Related Art
A pulse signal generator has been used to provide a pulse signal responsive to the position or speed of a moving object or a variety of operations. One example is a rotation detector that uses an electromagnetic/optical pick-up or Hole/magnetic reluctance element. The electromagnetic system, however, suffers from low output for zero-to-low speed rotations. The optical pick-up system requires a broadband d-c amplifier and a dust-proof structure. The Hole/reluctance system needs a plurality of elements and an amplifier. Some elements of the optical pick-up/Hole/reluctance system is too sensitive to temperatures to be used in the atmosphere that experiences large temperature changes.
Thus, these rotation detectors cannot detect the position or speed of a crankshaft or camshaft for an automobile engine for very low to high speed rotations. In addition, they are not suitable for use in the atmosphere in which they are exposed to large temperature changes or noise.
Japanese patent application Kokai Nos. 2000-101400 and 2000-101401 disclose pulse signal generators that use a magnetic element wire capable of producing large Barkhausen jumps as a detecting element from very low to high speed rotations. These pulse signal generators solves the aforementioned problems but needs further improvements for use in automobiles. The improvements include easy assembly, easy connection to the equipment that uses the pulse signal, the increased S/N ratio, and the increased load capacity, depending on the application.
Accordingly, it is an object of the invention to provide a pulse signal generator capable of solving the aforementioned problems and suitable for automobile application, a coil bobbin for the pulse signal generator, and a method of making the coil bobbin.
According to one aspect of the invention there is provided a pulse signal generator comprising a unit for generating a magnetic field, said means including at least one magnet; a magnetic element wire provided in said magnetic field and capable of producing large Barkhausen jumps; a coil bobbin molded integrally with said magnetic element wire and a pair of output terminals as a unit; and a wire coil provided around said coil bobbin and responsive to said large Barkhausen jumps to output a pulse signal across said output terminals.
According to another aspect of the invention there is provided a coil bobbin for a pulse signal generator including at least one magnet for generating a magnetic field, a magnetic element wire provided in said magnetic field and capable of producing large Barkhausen jumps, a wire coil provided around said magnetic element wire and responsive to said large Barkhausen jumps to output a pulse signal across a pair of output terminals, said coil bobbin comprising a coil section molded integrally with said magnetic element wire and a base section molded integrally with said terminals; said terminals each having a coil connection portion to be connected to said wire coil and a circuit connection portion to be connected to an outside circuit; said wire coil wound around said coil section, with opposite ends thereof connected to said coil connection portions.
According to still another aspect of the invention there is provided a method of making a coil bobbin for a pulse signal generator which includes a magnet for generating a magnetic field, a magnetic element wire provided in said magnetic field and capable of producing large Barkhausen jumps, and a wire coil provided around said magnetic element wire to generate a pulse signal across a pair of output terminals, said method comprising the steps of integrally molding a coil bobbin having a coil section around which said wire coil is wound and a base section with a through-hole provided near its front end such that said magnetic element wire runs through said coil section to said base section past said through-hole; and cutting off a portion of said magnetic element wire that lies in said through-hole.
According to an embodiment of the invention, the coil bobbin further comprises a flange section to form a reinforcing portion between said flange section and said base section, said wire coil wound around said coil section in a single layer but in a plurality of layers around said reinforcing and coil connection portions.
According to another embodiment of the invention, the flange section has a notch for facilitating transition of said wire coil from said plurality of layers to said single layer.
According to still another embodiment of the invention, the base section has a through-hole near a front end thereof, enabling to cut off a portion of said magnetic element wire embedded in said coil bobbin that lies in said through-hole.
According to yet another embodiment of the invention, the coil bobbin further comprises a tip section, said tip and base sections each having a flat face for positioning said magnet.